body {
    padding: 10px;
}

button {
    float: right;
}

.layui-btn-sm {
    float: left;
}

#button {
    position: relative;
}

#button button:nth-child(2) {
    background-color: red;
}

#button button {
    position: absolute;
    top: 0;
    bottom: 0;
    margin: auto;
}

.layui-btn+.layui-btn {
    margin-left: 0px;
}